1. Field of the Invention
This invention relates to a lock mechanism in an IC socket which includes an IC press cover to be closed over a socket substrate and a lock lever for holding the IC press cover in its closed state.
2. Brief Description of the Prior Art
In a conventional IC socket comprising a socket substrate and an IC package placed on the socket substrate and in which a contact relation between the socket substrate and the IC package is obtained by exerting a force directed downward on the IC package, the socket substrate, for example, is provided with an IC cover pivotally attached to one end of the socket substrate and a lock lever pivotally attached to the other end thereof. The lock lever is brought into engagement with one end of the IC press cover closed over the socket substrate to maintain its closed state by pivoting the lock lever forwardly. The lock lever is provided with an operating portion projecting from the vicinity of a free end of the lock lever in a forward direction or along an upper surface of the socket substrate. The lock lever can be pivoted rearwardly so as to be disengaged from the IC press cover.
The lock lever is normally resiliently supported by a spring in the direction of engagement (in the direction where the lock lever pivots forwardly) and the engagement between the lock lever and the IC press cover is released by a rearward pivoting of the lock lever against the resilient force of the spring.
When a number of IC sockets are arranged in parallel rows on a wire board, if the operation portions of the lock levers project from the upper surfaces of the socket substrates, large spaces must be provided between the adjacent substrates, thus giving rise to a problem in that in a burn-in test for carrying out a large number of measurements of IC at a time, for example, accommodation capacity in a furnace of a constant temperature is jeopardized.
Recently, a method has been adopted in which the lock levers of a large number of IC sockets arranged on the wire board are all disengaged at the same time by a robot arm. However, because the operating portion projects upward from the socket substrate, the robot arm must be moved horizontally along the upper surface of the socket substrate in order to exert a force on the operating portion. In this case, a complicated control is required in which the robot arm waiting in an upper position is first lowered and then moved in the horizontal direction. Furthermore, when an obstacle exists on the upper surface of the socket substrate, the automatic disengagement mentioned above becomes difficult.
The projection of the operating portion along the upper surfaces of the socket substrate and the IC press cover is an obstacle in obtaining a sufficient pivoting of the operating portion and the lock lever so much so that an insufficient engagement, etc. may occur. Moreover, it is difficult to adopt a method in which the robot arm can be merely lowered in order to release the engagement.
The present invention has been accomplished in order to overcome the above-mentioned problems.